Hi All,
I am not sure if I completely understand your application, but how I am interpreting it, there is a spinning shaft. Does this shaft only spin one direction?
If so, could you make you coupling a 2 piece threaded male and female with either a left or right hand thread with hex flats to torque the two male and female pieces to 150-200 ft/lbs, thus when the forces are greater then the thread unscrews itself.
If the shaft spins both directions then make the couple out of 3 pieces with both left and right threads torque as above.
Tofflemire